In the near future, broadband air-ground (A/G) communications will be used by civil aviation aircraft flying over crowded continental areas such as Europe and North America to access a variety of services, ranging from safety- of-life to infotainment applications. This paper investigates the feasibility of extending this coverage via air-air (A/A) multihop communications over oceanic, remote and polar regions, where no such infrastructure is available, so that aircraft flying over these areas can access the ground services without having to use an expensive high-delay satellite link. We focus on a particularly attractive scenario, the North Atlantic Corridor, and use realistic flight data to extract statistics about the dynamic topology of the airborne ad hoc network, such as connectivity and link stability. In addition, we assess the performance of greedy forwarding in the aeronautical environment and show that, under moderate connectivity, this technique delivers almost all packets to their destinations with a minimum hop count.